Tutoring lesson
by Takaluca
Summary: Lily needs help with her homework. Good thing her older sister is right next door. (One-shot)


It was a usual Sunday morning for the Loud House. Well, except it wasn't as Loud anymore. It made sense, after all. Most of the Louds have already moved away from the house. They've grown up to go to college and chase their dreams. Apart from the parents, only the two youngest siblings still remained. While it had certain advantages, it could get lonely pretty easily; especially since one of them was usually too busy with her research.

Lisa was in her bedroom, typing notes on her computer, doing her research. The sun appeared in all of it's glory on a clean sky, shining the whole room. Even if she wasn't working with her chemicals right now, she wouldn't ditch her lab coat. Force of habit, maybe.

"After mixing pentyl ethanoate with water under acidic conditions, the hydrolysis if the ester will product a carboxylic acid and an alcohol, which are ethanoic acid and pentanol, respectively. And with these compounds…"

Suddenly, she heard a quiet knock on the door. The 17 year old stood up from her chair and reached for the doorknob. On the other side, her 14 year old sister was standing. She was wearing a plain light purple T shirt and a pair of black jeans, and only socks on her feet. Her blonde hair reached a little past her shoulders, and she had a smile on her face.

"Greetings, younger siblings. Is there any situation that requires my assistance?"

"Hey sis, I, uh… could you help me with my homework?" She asked, shyly.

"Hmm..." Lisa looked back at her computer, rubbing her chin, before nodding. "I could definitely interrupt my researching for a brief period of time."

Lily escorted Lisa to her bedroom, which was Luna and Luan's old bedroom. After Lynn left, everyone could have a bedroom of their own. Since Lisa's equipment was too much to move, they decided it was easier to just move Lily instead. She changed most of the design. After all, music and comedy weren't exactly her things. There was a desk near the window, with a lamp, a pencil case, a few papers and a notebook scattered around.

"So, which questions are vexing you?"

"None, actually. The questions are okay, I'm struggling with the answers."

Lisa facepalmed and giggled a bit. "And I thought Luan was a comedienne. Now let's see what we…"

Lisa took a quick glance on the homework. It was Ninth Grade Physics. The subject somehow everyone in her family struggled to understand. Yet, she was always glad to help them understand. The main topics were constant velocity motion and constant acceleration motion. She gave a lot of classes on those to her siblings.

"Well then, tell me which of these answers is, ironically, the problem."

Lily showed her a list. A few exercises were marked on it, alongside some formulas and scrambled numbers. Lisa read them, and she realized she'd be able to explain it to her using only the first 2 exercises.

1- If an athlete runs at an average speed of 8 m/s, how long will she take to run 960 m? Express the result in both seconds and minutes.

2- A cyclist starts his morning ride and after 10 seconds his velocity is 7.2 km/h. At that moment, he sees a dog approaching and slows down for 4 seconds until the bicycle stops. Calculate:

a) The acceleration until he begins to slow down.  
b) The braking acceleration of the bike.  
c) The total distance traveled.

"The teacher explained some other ones in class, and sent this as homework. My friend gave me the answers, but I just don't know how to reach them. I know the formulas, but I can't use them. Physics only makes our lives harder. It doesn't make sense! Why can't we live without knowing all this stuff?" She exclaimed, angrily.

"Okay, please calm down. Take a deep breath, and let's handle this rationally." Lisa said, rubbing her chin. "Do you understand what velocity and acceleration is?"

"Of course. I mean, yeah… no, not really. I do know, but it's hard to explain…"

"Maybe you just need to see things from another perspective…" Lisa was thinking. "A hands on lesson will suffice. Put your shoes on, grab your homework and a pencil, and meet me downstairs" She ordered, and went back to her room. She grabbed a chronometer, took off her lab coat, revealing her green shirt, and put on her scuffed p brown shoes. Lily was waiting for her when she came downstairs.

"If we're going outside, shouldn't we warn mom and dad?" Lily asked

"We should let them rest." Lisa replied. "we'll be back before they wake up." Lisa assure, as she guided them both out of the house, Lisa took a chronometer and started it as soon as they began walking quickly.

"What's that thing for?" Lily asked.

"It's a chronometer. You'll understand it later. For now, let's determine what speed is."

"It's like, how quick something is?" she asked.

"Basically yes. Speed is, in practical terms, how far you can go in a certain period of time." Something caught her attention. "For instance, you see that sign that says the speed limit?"

"Yes. 30 miles per hour."

"That means a driver has to take at least one hour to drive 30 miles." She explained. "When we are talking about constant velocity motion, it means we never change our speed."

"So, like, in a car?"

"Yes, But it's not necessary. I'll show it to you later." They reached the end of the block, and they stopped, with Lisa also stopping the timer. "We took 50 seconds to walk this distance, and I know we walked one block. Which, in metric terms, is approximately 100 meters. If we can go 100 meters in 50 seconds, how much can we go in one second?"

"What is a meter?" Lily asked. "I mean, I hear it a lot, but I never understood what exactly it is. People don't use it."

" _Only we don't use it_." Lisa said to herself… "So, the meter is a measurement unit, just like an inch, a foot, a yard, or others. The difference is that all of those are part of what we call imperial systems, while the meter is part of the metric system."

"So, it's just a way to calculate distance?"

"Precisely. One yard is approximately 0.9144 meters, and one meter is 3.3 feet, so 1.1 yards, clear?"

"Uh…"

"On second thought, don't worry about it. We already have calculators and other machines that conversions for you. If you have a measure in meters, just use it in meters. So, back to my first question, if we go 100 meters in 50 seconds, how much do we walk in 1 seconds?"

"Uh… 2 meters?"

"Yes. We would be walking 2 meters each second. And which is the unit of velocity your friend used in her answer?"

"Meters per seco…" Lily's mouth went wide open. "Wait a second!" She exclaimed.

"It's not a coincidence that velocity is meters per second, or miles per hour. It's the distance unit by the time unit." Lisa said with a smile, knowing her sister understood.

"I never noticed that." Lily wrote on her notebook.

"Now, if we were at 8 meters per second, and we don't change our speed, how many seconds would we have to be walking to reach 960 meters? Do it in your head."

Lily scratched her head. "Uhh… I don't know."

"Okay, to make things easier, take it one step at a time. How much time would it take to walk 96 meters?"

"Uh, 12?"

"Yes. Now, if we multiply 96 by 10, we have 960. So we multiply 12 by 10, and we have…"

"120 seco…" Lily noticed the answer matched her friend's, and her eyes went wide. "How are you doing this?"

Lisa rolled her eyes. "Physics is not random, it's based in experimentation and logic. You can't memorize it, you have to understand it. For instance, have you ever heard of the triangle rule of constant speed?"

"No, what's that?"

Lisa took the notebook and draw a triangle, cut the upper part, and split the rest in half. She wrote the letter D on top, V on the left, and T on the right.

"Use this. You cover what you want to find. If it's side by side, you make one times the other. If they're above each other, you divide. D stands for distance, V for velocity, and T for time"

Lily began analyzing, and realized it matched the formulas. "This is so much easier than what the teacher told me!" she said excited.

"Glad you understand it. It took a lot longer with Leni." Lisa commented. "Now, let's get home, there's another principal you need to understand - acceleration."

They quickly went back to their house into the backyard. The house blocked the sun, making the whole area a bit darker. " Take a seat."

Lily sat on the grass, using the wall to lay her back on.

"Acceleration is, by definition, the variation of speed on a certain period of time. So, if I'm standing still, and I begin walking, that means there's an acceleration. In the condition you're studying, the acceleration is constant, which means is always the same. It's similar to what I showed you, except it's not speed's value that doesn't show variation."

"Sorry, I don't understand."

"Think like this." Lisa suggested, as she began walking in circles. "Every second, my speed increases a bit," she begin walking steadily faster. "But my speed is increasing the same value, and this value we add to speed each second is acceleration." she said as she was running. "Or, you can compare two different speeds, and how long it took, to discover acceleration."

"Oh, now I see it!"

"But it's not only to increase velocity." She began going slower. "It also includes moments when we go slower." She fully stopped. "The only difference is, the acceleration is negative. Unlike velocity, which is negative when going backwards. I had to teach Lynn this way. Sports always made her understand easier."

"Okay, but how do apply it to this?"

"You have a speed of 7.2 km per hour, or 2 meters per second, the speed we were walking. The man went from speed zero to speed 2 in ten seconds. There's an equation specifically for this case."

"Oh, I have it here!" She turned the pages. " _Vf=Vi+ A.T?"_

"Yes. Vf stands for the final speed, or 2 meters for second, Vi is the initial velocity, which we consider it zero, A is the acceleration, and T is the time. Appling all the numbers, you'll find you have an acceleration of 0.2 meters per second squared. The same applies for the second case, the only difference is that the acceleration is negative, because you lose velocity, and the time is shorter."

"Okay…" she began writing. "Yeah, I can do this. But how about the last one? How about space?"

"We have two ways." Lisa approached Lily and took the notebook. "We can do it the expensive way, or the cheap way."

"What?"

"Ever heard that time is money?"

"Yeah?"

"Well, in one method we don't need to know time. So, it's used for those who don't have money."

"Are you serious?" She giggled a bit.

"I am. Luna found it was a good way to remember. You can use either the space equation, Xf = Xi + Vi.T + ½.A.T^2, where Xf is the final distance, and Xi is the initial distance, or Torricelli's formula, Vi2=Vi2 + 2.A.(Xf-Xi). If you can fit every information you have in there, you got your answer."

"Okay, I think I can do this… which one should I use?"

"The easier one, because in the end, the answer should be both the same. Just remember, you have to calculate both moments, when speed increases, and when it decreases, to find the exact distance."

Lily took a couple minutes to do the calculations, as Lisa just stood by her side. After a few moments, Lily'd dug up the solution, but it didn't matched the one she wrote, which came by her friend, and Lily made a look showing a bit of confusion and disappointment.

"Dang it, it didn't worked. I don't get it, what's wrong here?" Lily said, as she threw her notebook on the grass.

Lisa went and picked up the notebook and adjusted her glasses. Checking carefully every number, concept, formula and even if the signal should be positive or negative. After a few moments, she returned the notebook to Lily.

"So, what's wrong?" Lily asked, with the back of her pencil, which had an eraser, pointed towards the notebook, ready to erase her whole effort.

"Your friend's answer." Lisa simply said.

"Really?" Lily asked. "You mean I…"

"I couldn't find a single mistake in there. And you know me." Lisa said, with a smile. "I don't know what she did, but it's not right."

"Oh my god, thank you!" Lily exclaimed. "It's much easier now!"

"If I had a penny every time I heard that, we'd be living in Beverly Hills" Lisa said. "I had to learn how to find ways to make things easier when Leni couldn't understand algebra."

"You're the best, sis!" Lily hugged her sister for a few seconds, before standing up. "Now if you excuse me, i think I'll try the rest on myse-"

"Wait!" Lisa stopped her. "There's one more thing I want to show you, wait here for a second."

Lisa dashed inside, to come back a few seconds later, with a key on her hands. "Come on, let's go."

"Where exactly are we going?" Lily asked.

"You'll find it out." She sat down in the driver's seat. "You'll probably like it."

"You're teaching me how to drive?!"

"As if. Wait until you're 16, then that might happen." Lisa teased, and Lily gave her an angry glance. "What? I got the same answer from the twins when I asked."

"You're not Lola or Lana." Lily complained. "And you won't be here to teach me."

"And I will be in jail if I allow a 14 year old to drive." Lisa replied. "And they won't let me conduct my experiments in there, so I'd rather not wind up in there. Come on, now. Let's go."

Lily entered the passenger's seat. "Aren't you even going to give me a hint?"

"Nope. You'll find out later."

Lily made an angry expression.

Lisa turned her head. "Be a bit patient, and I may teach you how to drive when you're 15."

Lily relaxed a bit, the angry frown being replaced by a small smile. "Don't worry, we won't be going too far. In the meantime, try doing your homework if you want to."

Lily took out her paper, a pencil, and a folder to have something to write on. "Alright, it shouldn't take too long now that you've helped me out." She then set to work as Lisa revved up the engine and started driving.

"Wow, Lana really _did_ do a good job. Even I can't understand how this old thing didn't just die on us. And it sounds as good as new." Lisa mused out loud.

"Yeah, that's Lana for ya." Lily said. Suddenly, a somber feeling washed onto the youngest Loud and the smile disappeared. "When she and Lola were still home, anyway…"

"Yeah… it's been a while," Lisa agreed. "Just like all the others…"

"I miss them all… when we were all together, you know? Or at least, since Lynn was still here. I don't remember much further from that." She looked up from her work. "But at least you're still here, Lisa."

"Well, yes." Lisa said. "I don't know for how much longer, though."

"Yeah…" Lily let out a sigh and went back to the homework, but slower now.

"Hey, we still have time." Lisa noticed Lily being a bit sad. "Let's make the best of it. Who knows, maybe a zombie outbreak takes place next month, and we both get stuck here."

"Heh, yeah. Sounds like something Lucy or Lincoln would have said."

"Well, that's what Lincoln said." Lisa said."

"Ah, makes sense."

A few more minutes went by, Lisa driving, and Lily focused on her calculations. The former parked the car and unlocked it. The sun was slowly disappearing behind the buildings and hills far away, with a cool breeze following to set up a refreshing night.

"Okay, here we are, Royal Woods Library." Lisa said. "Huh, still remember when they said it was my second home."

Lily opened the car door and climbed out, closing the door behind her. "Yeah, I can see why they'd say that."

"True. You know why this is one of my favorite places?"

"'Cause there's a lotta books and it's quiet, and stuff?"

"That too. But it's also because it's across the street from one of the best places in the city." She pointed to a modest ice-cream parlor across the street. "Come on, let's go."

Lily perked up upon reading the words "ice cream" on the sign above the entrance She happily followed suit behind her older sister. "Ice cream? I didn't know they had it near the library. How long has it been there, anyway?"

"As long as I first came here, I think. It's just you never came here. Or at least you don't remember it."

"Huh, and to think that I didn't even know until now."

"Then come with me. You won't believe how good it is."

The two entered the ice cream shop, immediately being hit with fridge air. It was a small place, only three tables before the balcony.

"So, what flavor piques your taste buds?" Lisa asked.

Lily pondered the question, looking over at the wide array of choices. "Hmm… I think I'll get Rocky Road."

"Hmm, good choice!" Lisa approached the attendant. "Two Rocky Roads, please." she handed her the money.

The attendant took the money and handed over the treats. Lisa headed back to Lily and the two took a seat at a table, immediately digging into the dessert.

"Ahh, I still remember the first time I tried one of these." Lisa said as she lightly spooned it. "It still gets better every time."

"I've actually never tried it before, just kept hearing about it and wanted to try it. It's pretty good." Lily commented.

"Just glad you liked it." Lisa said. "We don't hang out that often, and we used to share the same room."

"Yeah, I know. And I remember that the Loud house used to be much louder." Lily replied.

"You know, I never thought I'd have this 'big sister' role. Being the second youngest, I always had someone with me. Sure, I took care of you, but now there's only the two of us…" Lisa took a small break. "I think it's time I officially said it: I do really enjoy your company."

"I like being with you too, Lis. And yeah, it feels so recent that the twins were the oldest sisters here."

Lisa finished the last bit of her desert. "Just remember sis, whenever you need, you can ask me, school related or not."

Lily finished her ice cream as well. "Will do. And well, thanks for helping me out with the homework today. Just a few hours ago it was almost like hieroglyphics to me!"

"They all said the same thing," Lisa giggled. "Take some comfort in the fact that you aren't suffering alone. Now let's go back home."

With that, they headed back to the car and back to the not-as-Loud house. They both went upstairs, and Lily was about to head into her room, when…

"Hey, sis…" Lisa called her.

"Yeah?"

"Don't want to finish your homework in my room? I can help you if you have any other doubts, and we can keep each other company."

Lily blinked, and after a second she smiled and nodded, as she entered the room and Lisa closed the door.

 **Hey guys. Taka's back, and I'm not dead. Nothing much to say, just a one-shot I wanted to do. Hope you guys enjoyed it. Special thanks to WolfyTheRuff and RainCourt for helping me writing and editing it. Well, guess that's all. Leave your thoughts on it, and I might do more stuff like this, if you all enjoyed. See you guys later.**


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